Zinc alloy



Patented Aug. 11, 1931' PATENT OFFICE UNITED STATES LELAND E. WEMPLE, OF CHICAGO, AND FLOYD A. WARREN, OF PERU, ILLINOIS ZINC ALLOY No Drawing.

Our invention relates to new and useful alloys of zinc whose advantages will be hereinafter set forth. The alloy is prepared by adding to 100 parts of zinc from to 2% 5 parts of metallic copper and from 1/100 to 2 parts of antimony. The alloy should be free from aluminum or magnesium, preferably completely, but in any event in pro rtions so substantial as to affect adversel t eir valuable characteristics hereinafter escribed.

The use of zinc, particularly when rolled into the form of sheets or strips, is limited because of its low tensile strength, its slight hardness, and the rapid dulling of its surface. These disadvantages are overcome if there be added to the zinc both copper in the propor- -tion of to 2 parts, but preferably 4 to 2 parts, and antimony in the proportion of ,1/100 to 1 part, altho up to 2 parts may be 20, used to advantage and is within the scope of our invention. An alloy thus produced may be rolled into sheets or strips whose surface can be brought to an attractive condition by polishing and have a much higher tensile strength than sheets or strips rolled from zinc or known zinc base alloys. At the same time the natural advantages of the zinc, and particularly its ductility, are not reduced, in any event, to any appreciable or substantial extent.

The zinc used in the roduction of the alloy may be either a hig grade zinc such as electrolytic zinc, or the lower grades of commercial slab zinc or spelter which should, 5 however, not contain ingredients in quantities which detrimentally aifect the alloy. For instance, the presence of more than .60% of cadmium or 04% of iron renders the zinc too brittle for rolling into thin gauges. How- 4o. ever, the presence of less than .60% of lead, a frequent impurity in commercial zinc, may be disregarded as its presence in such amounts has no material efiect upon the alloy. The presence of even a small trace of aluminum causes the alloy, after rolling, to develop cracks and to disintegrate. For practical purposes we prefer to use a grade of spelter known in the trade as maximum iron content is 03%, maximum lead content 20% and maximum cadmium Intermediate whose Application filed January 21, 1981. Serial No. 510,321.

content .50%, but not more than a total of .50% of all such metals, and which is substantially free from aluminum and magneslum. We may, however, use to advantage the grade of spelter known as Brass special (maximum impurities, iron 03%, lead .60%, cadmium .50%, total not over 1.00%), or the rade known as High grade (maximum impurities, iron 03%, lead 07%, cadmium 0 07%, total not over .10%). For specifications of these three grades of commercial zinc as laid down by the American Society for Testing Materials see Metal Statistics 1930, page 413. r When commerical zinc which contains no appreciable amount of cadmium or iron, especially electrolytic grade, is used, we prefer to add a small quantity of either or both of these elements for the purpose of increasing the hardness and tensile strength. 'The exact proportion of copper and of antimony will depend upon the particular qualities of the alloy to be produced and also upon the various conditions of the process, for instance, rolling, to which the alloy is to be subjected. The particular proportions may easily be adjusted by simple experiment until the correct proportions suitable for the desired alloy are determined.

Example 1 Tensile strength with the grain 33,600lbs. sq. in. Rockwell hardness 95 Dynamic ductility 320 When the same commercial spelter is rolled down to gauge .050 it has a tensile strength of 24,300 pounds per square inch, a dynamic 2 Example 2 2 pounds of commercial zinc are melted in an electrically heated crucible, then 120 grains of copper and 30 grains of antimony are added and thoroughly mixed with the molten zinc. The molten allo is cast into a slab and cross-rolled to .050 t ickness as in the rolling of commercial sheet zinc. The assay and physical properties of the rolled alloy compared with commercial zincrolled 1n the same way to llke gauge are as follows:

Com- Alloy merctal zinc.

Gauge-inches- 050 050 Assa Per cent iron .024 .024 Per cent lead .15 .258 Percent cadmlum 132 124 Per cent cop r .886 None. Per cent ant ony .225 None. Zim- Balance Balance.

Ph calpio rtlesazdnem, ockwell 95 86 Ductlllty, dynamic 370 325 Attention is called to the fact that these physical tests are slgnlficant only when compared with ordinary Z1110 rolled under identical conditions. For instance, the alloy of Example 1 would, if rolled to a thinner gauge, have its tensile strength increased but its duetility decreased.

Sheets rolled at customary zinc rolling temperatures and made of alloys within the proportions given exhibit a marked freedom from the ordinary strain crystals ap caring in rolled zinc. If sheets made of such alloys are subjected to the action of the standard etching solution for zinc, photo-micrographs (250K) thereof disclose a striated formation remarkably free, and in some cases apparent- 1 almost absolutely free, from such crystals.

's standard solution consists of chromicoxide 20 grams, sodium sulphate 1.5 grams, and water 100 cc.

If such sheets be submitted to a special etching solution consisting of 10 grams of chromic-oxide, 1.5 grams of sodium sulphate, and 100 cc. of water, the hoto-micrographs show a surface made as ii by very fine stippblling, the striations being practically invis- 1 e.

vantages of our alloy begin to diminish. As

already stated, we prefer to use for commercial purposes 4 to 2 parts of copper. We are at present of the opinion that the copper and antimony are, when used within the limits herein specified, held in solid solution by the zinc grains or lproduce compounds with one another or wit the zinc itself which are in turn held in solid solution by the zinc grain. The coppgr and antimony should not, for best results, used in so large an amount which would result in the production of a seconda crystalline structure in the alloy, thus destroying its homogeneity and rendering it brittle. It is, however, to be understood that the temperature conditions under which the alloy is cast or mechanicall worked may infiuence the degree of solubility of these metals in the zinc grain.

So far as we know, no alloy of zinc cop r and antimony in the proportions specltlifd has ever been used commercially for producing articles by mechanically working, for instance, bfy extrusion, by s inning, b drawing, by orging or by re 'ng into s eets or strips, for all of which purposes our alloy is specially suitable. We therefore claim as novel a mechanically worked zinc product made of our alloy.

Having described the invention what we claim as new and desire to secure by Letters Patent of the United States is:

, Asa composition of matter an alloy characterized by the fact that it is of substantially greater hardness than zinc and capable of being mechanically worked, composed of zinc 100 parts, copper to 2% parts and antimony 1/100 to 2 parts.

In testimony whereof we have hereunto set our signatures.

LELAND E. WEMPLE, FLOYD A. WARREN. 

